1) The authors postulate that the relationship between joint collaboration and sharing is crucial for understanding the origins of equality, both in ontogeny and phylogeny. Therefore, they investigate how children actively divide rewards after working for them in a collaborative problem-solving task.

Most studies on sharing involve windfall situations, in which resources are given to the children by a third party, with no work or effort involved. Moreover, many studies use a forced-choice paradigm with predefined allocation options, which does not allow for an assessment of how children themselves would actively negotiate over how to distribute resources with another person.

In contrast, Warneken et al.’s research is guided by the notion that people often have to work toward obtaining resources, and that they distribute those resources actively, rather than choosing individually between predefined options. Previous studies, they say, have not shown how children share resources in situations that might be the cradle of equality: actual joint collaborative activities with a social partner.

2) The experiment closely resembles sharing experiments with chimpanzees and other non-human primates. Warneken et al test children in dyads. Children have to perform a task together: they have to pull from both ends of a rope at the same time in order to bring a box close to them. In this way, they are able to get a reward (such as stickers or candy that have been placed in the box). In one condition, the box has two holes far apart, so that each child can get her reward without interference from the other participant. In a second (“clumped”) condition, the box has only one hole, and therefore only one child can access the rewards at a time.

3) Warneken et al. found that neither the reward type nor the opportunity to monopolize rewards in the clumped condition interfered with the children’s collaboration. 3 year-olds collaborate successfully in situations in which resources can be monopolized. The collaborative abilities of young children, compared with those of chimpanzees, are not constrained to the same extent by a tendency to monopolize resources.

Children predominately produced equal shares. They shared rewards equally most of the time, even when rewards could be monopolized more easily (clumped condition). At an age when children are just beginning to skillfully collaborate with peers, they already engage in sharing behavior that results in equitable outcomes.

4) What does it all mean? Competition over resources, the authors claim, is mitigated in human children (when compared with chimpanzees and other primates) by an emerging sense of equal sharing of the spoils, which enables successful collaboration even early in ontogeny. Thus, the authors claim that this study supports a Tomasello-like evolutionary hypothesis, according to which the emergence of cooperation is due not only to cognitive and behavioral skills, but also to a reduction in competition over resources. Competition over resources is mitigated in human children by an emerging sense of equal sharing of the spoils, which enables successful collaboration even early in ontogeny.

5) According to this study, children are capable of equitable distributions a very early age. Although many studies place the origins of equality at around 5, 6 or even 7 years of age, it all depends on how the concrete distribution problem is presented to the children. Warneken et al. present children with a collaborative, non-competitive situation. In addition, in this study the peer is present; the dyad works together in a problem solving activity (compare this with economic games that are played by a single present individual and an absent, anonymous, “invisible”). Even more, some of the dyads comprise children who know each other well, since they attend the same day-care center (they are not one-shot interactions, as in most economic games). All this seems to help even 3 year-olds to produce equitable outcomes early in development. The authors reach the conclusion that, perhaps, children learn to acknowledge each other’s right to gain equal resources in situations in which they collaborate to produce a mutually beneficial outcome that one person acting alone would not be able to achieve (this result is not proven by the experiment, in my opinion).

This is another crucial study by Tomasello and his team. The researchers designed games to be played individually by the toddlers participating in the study. The child and the researcher would play in parallel, side by side. At some point the child would need more resources to continue playing and these would have to be provided by the researcher; later the researcher would lack resources and the child would have the opportunity to either help the researcher or defect. As the authors put it: “we gave 2- and 3-year-old children the opportunity to either help or share with a partner after that partner either had or had not previously helped or shared with the children. Previous helping did not influence children’s helping. In contrast, previous sharing by the partner led to greater sharing in 3-year-olds but not in 2-year-olds.”

These results do not support theories claiming either that reciprocity is fundamental to the origins of children’s prosocial behavior or that it is irrelevant. Instead, they support an account in which children’s prosocial behavior emerges spontaneously but is later mediated by reciprocity.

It is not until 3.5 years of age that children modulate their sharing contingent on the partner’s antecedent behavior. Children first develop prosocial tendencies (already present in babies or young toddlers) and later those tendencies become mediated by reciprocal strategies. Helping and sharing emerge before children begin to worry about direct reciprocity. Later in development, they seem to become more sensitive to reciprocity, adjusting their prosocial behavior accordingly.

This is such a relevant and decisive article. From the very beginning it posits the all-important issue of ownership (about which we have talked repeatedly in this blog) in an extremely clear manner:

“Possession and property structure many, if not most, of our everyday interactions with objects. Young children (and even some animals) care about physical possession, and indeed many of children’s early conflicts with peers are over physical possession (…). By around 24 months, young children can reliably identify who possesses familiar objects (…), and their appropriate use of possessive language (“my milk’’, ‘‘mommy’s sock’’) suggests some nascent understanding even earlier than that.”

The authors then proceed to differentiate possession from property. Whereas possession has to do with physical control, property (or ownership) is a social an institution and, therefore, it is supported by social agreements to mutually recognize each person’s rights to possess things.

The authors also introduce a useful distinction between conditions of ownership (“under which conditions who owns what”) and implications of ownership (rights, commitments, entitlements). One my classify the existing literature and research on the development of ownership into studies that focus on conditions of ownership and studies that focus on implications of ownership.

In addition, the authors make the point that rules of ownership are supposed to have normative force in an agent-neutral way. This theoretical claim translates easily into an empirical claim: if children understand ownership rules as agent-neutral, they should protest transgressions against ownership when they affect a third party and not only when they affect their own interests.

How did they investigate whether children have this capacity? They used a three-party situation, involving the child, a puppet and an actor. The puppet was the agent that took either the child’s property or the actor’s property. The study found that 2 year olds protested when the puppet took their property or tried to throw it away; but 3 year olds protested also when the puppet took the actor’s property. The very fact that children protest such violation of property rights is supposed to involve an agent-neutral view of rules.

In the authors’ words: “Standing up for the property rights of a third party, using normative justifications on occasion, demonstrates (…) young children’s emerging understanding of the normative dimension of property as it applies to all persons equally in an agent-neutral manner. It is not just that I do not like it when someone takes or throws away an object that doesn’t belong to them; it is wrong.”

The authors conclude that, according to this study, by 3 years of age children understand the basic normative structure of property and property rights violations. This entails a basic understanding of institutional reality in Searle’s sense, and therefore of conventional norms and status functions. (This stick is a horse; this ball is mine; I’ve made a promise).

My only minor disagreement is that Tomasello sometimes refers to the institutional reality as “conventional”. I think one might distinguish between the moral domain, a conventional domain (arbitrary rules such as rules of etiquette) and legal or institutional norms that are neither moral nor conventional. Ownership, stealing, exchanges, contracts, membership, etc. all fall in this last category.

At some point I will write extensively in this blog about one of my central tenets: children’s everyday social experience is best understood when analyzed into three institutional dimensions that I call: inclusion, hierarchy and reciprocity.

For the time being, here is a little example that shows how these three dimensions are present in my son’s everyday interactions.

Inclusion: Starting at about 3 years of age, whenever I announce that I am going to do something (go shopping, eat some yogurt, cook, take a nap, etc.) he usually replies “me too” (“yo también”), “I’ll go with you” (“te acompaño”) or “Let me help you” (“te ayudo”). He is thereby including himself in a group (formed by two or more people); he is inserting himself, through speech, within an “us”, and assumes that the activity in question is not performed by me and by him at the same time but by a collective formed by both of us. By the way: Michael Tomasello talks a lot about this specifically human ability to do things together, that is, to cooperate (Tomasello, 2009). At about the same age he starts talking about his friends. For example he refers to his cousin F. by saying “mío amigo” (“my friend”); he also mentions frequently that “F. is my friend”. When he’s about to leave for kindergarten he mentions he wants to meet his friends to play (“voy a jugar con míos amigos”). To sum up: he acknowledges that there is a sub-group of friends within the larger group of human beings; he shares with his friends a type of experience (peer play) that is different from what he does with his older sister, adults, etc. He includes himself in this proto-community. At about 3 years and 4 months he says that his music teacher, Maxi, is my friend, because “we both have a beard”.

Hierarchy: There is also a hierarchic dimension in children’s everyday experience. L. differentiates between grown-ups and kids (“grandes” and “chicos”) in his speech; he also knows that grown-ups are entitled to a number of things from which kids are excluded (manipulating dangerous objects such as pots with boiling water or oil, drinking wine, driving, giving orders to other kids, staying up late, etc.) And it is clear, in many situations, that he would like to be a grown up (he says he’s “big”; he engages in pretend play in which he’s a grown-up).

Reciprocity: this dimension of institutional life is obviously present in many everyday episodes, both involving adults and other children. In this blog, we have discussed object trading and give-and-take games, and will continue to provide similar examples. We might also mention that reciprocity is strongly embedded in linguistic practices and language games such as mutual greeting, thanking and welcoming, etc., in which the participants’ roles are symmetrical and interchangeable.